1. Field of the Invention
The present invention relates generally to a vibration device, for example, such as a disk grinder, and more specifically to a vibration prevention handle used for the vibration device such that a small-diameter close-coiled and larger-diameter open-coiled helical spring is loosely fitted to the handle of the vibration device for prevention of the worker from its vibration and shock.
2. Description of the Prior Art
In a conventional vibration device, for example, such as a disk grinder, a handle or a grip is usually provided on either side thereof, as shown in FIG. 1. In this case, the disk grinder is supported by the worker when he grips the handle 2' by his left hand and the rear side portion 2 by his right hand or vice versa, and is used by the worker when he puts the rotating grinder wheel 3 onto a work piece under an appropriate pressure while moving the grinder right and left or back and forth.
In the prior-art disk grinder as described hereinabove, however, since the grinder wheel's grind angle (an angle between the grinder wheel surface and the work piece surface which has already been ground by the grinder wheel) changes according to the finished profile of the work piece, for instance, in the case of plane finish, the grinder wheel is moved in parallel with the finished surface of the work piece; in the case of the finishing or cutting of an external circumference or an angled surface of an axle, the grinder wheel is required to be handled with an appropriate grind angle. In addition, since the disk grinder ranges from 6 to 7 kg in total weight and the grinder wheel rotates from 6000 to 7000 rpm, a considerably strong vibration and shock is generated and is given to the worker through the handle, accompanying a centrifugal force, whenever the grinder is used for grinding work.
Because no effective countermeasures have been taken until now against such vibration and shock, the conventional disk grinder handle gives an unbalanced weight feeling of vibration and shock to the worker's hand or arm especially when the grinder is used with the grind angle changed by the worker, thus resulting in an occupational disease like vibration disease or Raynaud's disease (which occurs only in a user of the vibration devices). Without limiting the above-mentioned disk grinder, such disease inevitably occurs a worker uses an electromotive hammer, an impact wrench, an airmotive concrete breaker, etc.
The above-mentioned vibration disease has symptoms as follows:
(1) circulation trouble of the blood at the hand or arm to which vibration is directly applied;
(2) function trouble of the central nerve;
(3) trouble of the bones and joints.